Loop lock stitch shoe sewing machines



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LOOP LOCK STITCH SHOE SEWING MACHINES Filed Oct. 28. 1955 12 Sheets-Sheet 6 I H Jl L g L L IL [54 6],: av Q In men for *Jseph [0a 7zn zZZz' March 17, 1959 J. R. IOANNlLLl 2,877,725

LOOP LOCK STITCH SHOE SEWING MACHINES 7 Filed Oct. 28. 1955 lZ SheetS-Sheet '7 March 17, 1959 J. R. lOANNlLLl LOOP LOCK STITCH SHOE SEWING MACHINES 12 Sheets-Sheet 8 Filed Oct. 28. 1955 March 17, 1959 J. R. lOANNlLLl 2,877,725

LOOP LOCK STITCH SHOE SEWING MACHINES- Filed Oct. 28. 1955 l2 Sheets-Sheet 9 Inventor -c7 sephRJczhniZZZ March 17, 1959 J. R. IOANNILLI 2,877,725

LOOP- LOCK STITCH SHOE SEWING MACHINES Filed Oct. 28. 1955 l2 Sheets-Sheet l0 March 17, 1959 J, R. o m I 2,877,725

LOOP LOCK STITCH SHOE SEWING MACHINES Filed Oct. 28. 1955 12 Sheets-Sheet 11 1&20

Inventor March 17, 1959 J. R. lOANNlLLl 2,877,725

LOOP LOCK STITCH SHOE SEWING MACHINES Filed Oct. 28. 1955 12 Sheets-Sheet 12 In for 17588 .Raanzlli will! United States Patent LOOP LOCK STITCH SHOE SEWING MACHINES Joseph R. Ioannilli, Beverly, Mass., assignor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application October 28, M55, Serial No. 543,321

Claims priority, application Great Britain .luly 14, 1955 23 Claims. (Cl. 112-62) The present invention relates to lock stitch shoe sole sewing machines, and more particularly to improvements in the type of sewing machine which is provided with looking loop forming and inserting devices, rather than the type having a locking thread carrying shuttle about which each loop of machine or needle thread is passed in forming a conventional lock stitch seam. In certain of its features, however, the invention is not limited to sewing machines for operating exclusively upon shoes but is capable of use with other types of sewing machines for inserting loop lock stitch seams.

The objects of the invention include the provision of a hook needle, loop lock stitch shoe sewing machine which is capable of operating successfully about the threedimensionally curved sole margin of a shoe presented to the machine, with uniformly efiective results and with a degree of commercial acceptability equal to that ohtainable previously with a shuttle type lock stitch machine. Other objects are to improve the construction and mode of operation of prior loop lock machines in a manner to render them capable of inserting seams indistinguishable in appearance from those inserted by a prior conventional machine employing a shuttle or loop taker.

The usual practice in sewing outsoles to shoes is to employ a lock stitch sewing machine having work clamping and stitch forming devices to which a shoe is presented in inverted position with the bottom surface uppermost and unobscured, so that the operator for the machine may observe the appearance of the stitches being inserted at the tread surface of the shoe outsole constantly while a seam is being inserted. Accordingly, the machine is constructed with a work support which fits the space between the outflanged or projecting marginal portions of the shoe and the bulging portions of the shoe upper. A presser foot is provided which acts from above the work support to clamp the portions of the shoe operated upon about the sewing point. The machine is of necessity provided with a curved hook needle, which operates toward and from the unobscured tread surface of the outsole to withdraw loops of thread from the outsole and present them to a shuttle or loop taker, where they are interlocked with locking thread, the shuttle being mounted for operation in available space above the tread surface of the outsole. If an attempt is made to substitute locking loop inserting devices for the shuttle, it is necessary to retain the same spatial relationships and other requirements so that the usual practices for outsole stitching may be preserved.

Many diificulties peculiar to the operation of a shoe sole stitching machine, in general, result from two causes: first, from rapidly changing three-dimensional curvatures along the margin of a shoe sole; and second, from lack of flexibility and the resistance to easy penetration of the shoe materials operated upon. The operating difficulties due to both causes result in deflection of the needle from its proper path of movement and in improper cooperation of the needle with the other stitch ICC forming and Work manipulating devices in such machines. It is for these reasons that any commercially successful shoe sole stitching machine has, heretofore, been provided with a hook needle, which is arranged to have its thread loop transferred to the other stitch forming devices, while it is disengaged from the work operated upon, and while it is, therefore, less subject to deflection and relative displacement with relation to the other stitch forming devices.

Other diificulties, common particularly to outsole stitching machines, are attributable to the widely varying thicknesses of work required to be operated upon by such machines, it being necessary to vary the amount of thread provided from one stitch to another in accordance with the work thickness and to provide space for a maximum thickness of work intended to be operated upon by suitable clearance spaces and other adequate dimensions in the machines.

In order to vary the amount of thread provided for each stitch in certain prior loop lock stitch shoe sole sewing machines, they have been equipped with automatically adjustable stroke needle actuating mechanisms which withdraw more thread for thick work than for thin work and with a locking thread loop carrying finger provided to divide and to enter each loop of needle thread as it is tensioned between the needle and the previous stitch in the work. Such provisions, however, are undesirable where deflection of the needle occurs as a result of presenting a shoe to the machine, the movements required in presenting the shoe frequently changing the relationship between each previous stitch and the needle after it withdraws a loop from the work, to such an extent that the thread loop carrying finger fails to enter between the sides of the tensioned loop.

An obvious expedient to overcome the difficulty of failure on the part of the thread carrying finger to enter each needle loop with varying thicknesses of work in a loop lock machine is to provide the machine with a loop spreader for opening each loop of needle thread to a sufiicient degree that changing positions of the work in the machine from one stitch to another will not move the spread loop out of alinement with the thread carrying finger. The use of a loop spreader, however, for this purpose in a machine, in which the amount of thread withdrawn with the needle from the work is changed with varying thicknesses of the work, is detrimental to an accurate measurement of thread required for each stitch unless the loop spreader also has an operative stroke which is automatically adjustable proportionately as the thickness of the work varies. The provision of such adjustable mechanism for actuating the loop spreader, particularly where a similar adjustable mechanism already is provided for actuating the needle, renders the machine unusually complex. To provide an arrangement for coordinated adjustments of the mechanisms for both the needle and loop spreader, to insure accurate adjustment of thread measurement in direct proportion to the thickness of the work, overburdens the already complex structure and expense of manufacture for the machine beyond practicability.

In the accomplishment of the objects of the invention noted above, the difiiculties encountered have been avoided by the provision of a simply constructed loop lock stitch shoe sole sewing machine having a hook needle operating to a fixed retracted position with a loop of thread, a loop spreader for opening each loop of needle thread into a fixed triangular shape, and an automatically adjustable thread measuring mechanism separate from the needle for varying the amount of thread provided for each stitch, in which machine a locking thread loop carrying finger is connected for movement with a work clamping presser foot to change its position as the thickness of the work varies, so that the locking loop will enter each spread loop of needle thread at an ample distance from the surface of the work where the angles formed by the sides of the loop provide adequate clearance for the locking loop carrying finger to offset any possible change in the position of a shoe resulting from its presenting movements in the machine. If the needle is actuated to a fixed, withdrawn position and the loop spreader is actuated to bring the upper leg of each spread needle loop to a maximum height required for the thickest work intended to be sewn, then reliable entry of the thread finger is insured under all conditions in which the machine is intended to operate, the separate thread measuring mechanism serving the purpose formerly accomplished by the adjustable stroke needle actuating mechanism. Preferably, the locking thread carrying finger is supported on a carrier separate from the presser foot, connections being employed in one form of this feature between the thread finger carrier and the presser foot for actuating the two in unison.

Other features of the invention reside in a machine having a hook needle which is curved and which oscillates about a central stud and a presser foot having a fulcrum about which it swings toward and from the work, the locking loop forming and inserting devices having pivot connections disposed substantially concentric to the fulcrum of the presser foot lever. When so arranged, the movement of the presser foot will have a minimum reaction on the loop inserting devices.

These and still other features, including the adaptation of loop lock stitch forming devices for use with a clamp feed machine, consist in the devices, combinations, and arrangements of parts hereinafter described and claimed, the advantages of which will readily be understood from the following detailed description taken in connection with the accompanying drawings, in which Fig. l is a view in front elevation of the upper portion of a Goodyear outsole loop lock stitching machine embodying the features of the present invention;

Fig. 2 is a view in elevation on a somewhat enlarged scale, looking from the right side of the machine shown in Fig. 1;

Fig. 3 is a view in left side elevation and partly in section of the machine;

Fig. 4 is a sectional plan detail view of certain portions of the machine including one of the sewing shafts;

Fig. 5 is a further sectional plan detail view of some of the parts surrounding the sewing point in the machine;

Fig. 6 is a detail view on an enlarged scale of the parts surrounding the sewing point in the machine;

Fig. 7 is a sectional plan detail view of another of the sewing shafts in the machine, illustrating some of the actuating connections for the stitch forming devices;

Fig. 8 is an enlarged detail view of the lower end of a combined loop spreader and thread retractor in the machine;

Fig. 9 is a sectional plan view of the lower end of the loop spreader and thread retractor looking from the line IXIX of Fig. 8;

Fig. 10 is a sectional plan detail view of the feed carriage and associated parts of the machine, certain of which are shown in separated relation;

Fig. 11 is a detail plan view on a slightly enlarged scale of a locking loop inserting finger, illustrating its manner of operation in the machine;

Fig. 12 is a detail view in front elevation of the lower end of a locking loop detaining finger employed in the machine;

Fig. 13 is a detail view in left side elevation of a take-up and needle thread measuring mechanism employed in the machine;

Fig. 14 is a detail perspective view looking from the right and front and showing portions of the thread engaging devices surrounding the sewing point in the ma- 4 chine taken while the machine is at rest ready to receive a work piece;

Fig. 15 is a similar view looking from the left front of the same devices indicating portions of a welt and an outsole being operated upon;

Fig. 16 is a similar view of the same parts showing the operation of the loop spreader in opening a needle loop for entry of the locking thread loop carrying finger;

Fig. 17 is a similar view of the same parts showing the position of the thread carrying finger after entry within a spread needle loop while operating upon relatively thin work;

Fig. 18 is a similar view with the same position of the parts while operating upon relatively thick work;

Fig. 19 is a similar view of the same parts showing their relationship after entry of a detaining finger into a locking loop;

Fig. 20 is a further detail view looking from the left of the needle and loop spreader illustrating the thread being retracted from the hook of the needle by the loop spreader;

Fig. 21 is a detail perspective view showing the thread carrying finger after being withdrawn from the needle loop and while the needle loop is being contracted against the locking loop;

Fig. 22 is a similar view of the same parts showing the first stitch in a seam after being formed and about to be set in the work;

Fig. 23 is a detail perspective view of a portion of a shoe sole and a welt showing the tightening action of the first stitch in a seam; and

Fig. 24 is a time chart showing the operation of the stitch forming and other acutating devices in the machine.

The illustrated machine is of the same general construction and mode of operation as that disclosed in United States Letters Patent No. 1,169,909, granted February 1, 1916, upon application of Fred Ashworth, and No. 2,271,611, granted February 3, 1942, in the names of Fred Ashworth and Carl F. Whitaker. The machine is equipped with a curved hook needle 2 (see Fig. 3), a curved awl 4, a loop lifter and spreader 6 at the side of the work with the needle, a needle looper 8, a thread finger 10, a work feeding clamp comprising a work support 12 toward which the needle operates and against which the work is pressed by the work entering thrust of the needle, and a presser foot 14 (Fig. 2), a stitch setting take-up 16 (Fig. 13), front and rear thread locks including a needle thread clamp 18 and a guiding truck 20, and a needle thread measuring mechanism separate from the needle including a thread measuring arm 22, the position of which mechanism is automatically adjusted by the position of the presser foot while in engagement with the work, and a pull-off comprising an arm 24 cooperating with the measuring arm 22 to measure more or less needle thread as the work varies in thickness. In common with other shoe outsole sewing machines the presser foot acts at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support.

As distinguished from the machine of the patents, which is provided with a rotating shuttle or loop taker, for interlocking each loop of needle thread with a locking thread, the illustrated machine has, in place of its shuttle, a locking thread carrying finger 26 and a locking loop detaining finger 28 cooperating together to introduce and hold a loop of locking thread within each loop of needle thread after being withdrawn from the work by the needle. The loop detaining finger prevents displacement of the locking loop after being introduced by the thread carrying finger while the thread carrying finger is withdrawing from each needle loop. The operation of the other stitch forming devices otherwise is substantially the same as that of prior patents, except that the take-up 16 is in the form of an arm which is shorter than the take-up arm in the Prior patented machine, the

amount of thread given up to the needle as it retracts from the work and to the loop spreader as each needle loop is expanded being smaller than that required in a machine provided with a conventional shuttle or loop taker.

The feed clamp includes a swinging carriage 30 (see Fig. to which the work support 12 is secured, and a lever 32 to which the presser foot 14 is secured, the lever 32 being fulcrumed on a pin 34 supported in the feed carriage 30. To enable the work support and presser foot to feed the work, the feed carriage 30 is secured to an inclined pivotally mounted shaft 36 rotatable in a sewing head frame 38, the presser foot 14 clamping the work against the work support 12 during the feeding movement and releasing the work from clamping engagement while the work support and presser foot are being back fed. To retain the work in position during back feed of the presser foot and work support the awl engages the work and the needle and awl oscillate about a fixed stud 39 (Fig. 6). The feed carriage 30 is reinforced between its pivotal mounting and the work by the formation of flanges on the feed carriage slidingly mounted in slots 40 (Fig. 6) formed in removable side brackets 41 on the sewing head frame 38 at the sides of the feed carriage.

In the operation of the machine, while the work is clamped by the presser foot and work support, the awl 4 forms a perforation in the work (see Fig. 15), and the needle enters the perforation to receive a loop of thread from the looper and thread finger. The threaded needle retracts from the work to a fixed position with a loop of thread (Fig. 16), and the loop spreader and retractor opens up the loop of thread carried by the needle into fixed triangular shape, one angle of which is held by the needle as shown in Fig. 17. The locking thread carrying finger 26 then enters each spread loop of needle thread between the work and the upper leg of a spread loop which defines a plane substantially at right angles to the direction of feed and to the line of the seam inserted, to introduce a loop of the locking thread within the needle loop. After the thread carrying finger enters the needle loop (Fig. 17) the thread detaining finger 28 passes through the locking thread loop close to the thread carrying finger and prevents the locking loop from being withdrawn from the needle loop while the thread carrying finger is being retracted. Before the needle loop is contracted by the take-up against the locking loop held by the lower end of the detaining finger, the loop spreader moves rearwardly, releasing the spread needle loop (Fig. 19). The take-up then draws the released loop of needle thread toward the upper surface of the work. The combined loop spreader and thread retractor disengages the thread from the needle hook as the needle dips (broken lines, Fig. 20). Continued movement of the take-up as it approaches the lower end of its stroke contracts the loop of needle thread (Fig. 21) and draws the point of engagement between the needle loop and the loop of locking thread, first securely against the upper surface of the work (Fig. 22), and then to a predetermined distance beneath the upper surface of the work to hide the locking loop within the substance of the work (see Fig. 23). The stitch thus formed is complete without withdrawing the free end of locking thread from the needle loop.

In preventing withdrawal of the locking thread from the needle loop, the loop detaining finger 28, at its lower end, engages with and forms an indentation in the upper surface of the work, the movement of the detaining finger toward the work being regulated exactly to engage the work with certainty, regardless of its thickness, in order that the locking thread running between the thread carrying finger 26 and the work may not escape. The movements of the thread carrying finger are coordinated with those of the loop detaining finger, the detaining finger always engaging the locking thread exactly at the same time in each sewing cycle regardless of the thickness of the work. To these ends both the locking thread carrying finger 26 and the loop detaining finger 28 are connected for movement with the presser foot 14, so that when the presser foot engages the work both the thread carrying finger and the detaining finger will be located at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work in the proper relationship to perform their functions reliably and effectively.

The thread carrying finger 26 moves in substantially a horizontal direction, although somewhat toward the work as it enters each needle loop, but the loop detaining finger 28 moves in a more nearly vertical direction. The thread carrying finger thus moves in a path at a distance from the presser foot engaging surface of the work, parallel with the upper surface of the work and the loop detaining finger, substantially perpendicularly to that surface of the work. Accordingly, it is possible to contract each needle loop while the thread carrying finger is within the needle loop and until the needle loop actually is ready to be drawn against the locking thread loop, thus guiding the contracting needle loop and insuring uniform movements of the needle loop before actually being pulled into the substance of the work with the loop of locking thread (Fig. 23). The lower end of the loop detaining finger engages the work by entry into a needle and awl receiving opening 42 in the presser foot (see Fig. 10), the feed of the work actually taking place while the loop detaining finger engages it. The loop detaining finger engaging the work also assists in feeding the work. To these ends the locking thread carrying finger is connected for movement toward and from the work with the presser foot as the work varies in thickness and the loop detaining finger is mounted for movement directly on the presser foot lever 32.

As a result of the mountings for the locking thread carrying finger 26 and the locking loop detaining finger 28, work of varying thickness, such as encountered in a shoe, may be operated on successfully. As shown in Figs. 17 and 18 work of thin or thick materials is effectively sewn without making any manual adjustments in the machine.

The locking thread carrying finger 26 is formed with a curved lower end provided with guides for the thread and has a straight shank adjustably secured within a split clamp at the forward end of a forwardly projecting rod 44 (see Figs. 6 and 10). The rod 44 is held by a bolt 45 within a bore of an arm 46 rotatable at the lower end of an inclined pin 48 rotatable in a lug at the forward end of a vertically swinging carrier 50. At its rearward end the carrier 50 is clamped to the reduced right end of a horizontal stud 52, the enlarged shank of which enters a bearing on the left side bracket 41 (Fig. 10), about the axis of which bearing the thread carrying finger moves horizontally toward and from each spread needle loop. The arm 46 is adjustably clamped to a plate 54 also mounted for rotation on the lower end of the pin 48, the plate 54 having an arcuate slot through which passes a screw 56 engaging a threaded opening in the arm 46. The plate 54 and the arm 46 are clamped together by the screw 56 and form a mounting lever for the thread carrying finger 26 by means of which the finger 26 is moved to introduce a loop of locking thread and to retract from each spread loop of needle thread, indicated at 57, leaving the locking thread loop within the needle loop. The lower end of the thread carrying finger between its shank and curved portion has a sleeve-like guide 58 for the thread and an eye at its lower extremity through which the locking thread, indicated at 60, passes.

For actuating the locking thread carrying finger 26, the plate 54 of its mounting lever has projecting from it a ball-headed stud 62 surrounded by a socket in one end of a link 64 (see Fig. 6) having a similar socket at its other end surrounding a ball-headed stud 66 at 7 the lower arm of a lever 68 (Fig. 3). The lever 68 is rotatable on the left end of a shaft 70 secured in a lug 72 on the head frame 38, and the hub of the lever is divided to straddle the frame lug. A horizontal arm of the lever 68 carries a roll 74 engaging a groove in a cam 76. The cam 76 is secured to a sewing shaft 78 which rotates in unison with a second sewing shaft 80.

To cause the locking thread carrying finger 26 to introduce a loop of locking thread within each needle loop and to be raised from the work with the presser foot 14 so that the thread carrying finger will enter each spread loop of needle thread at a uniform distance from the upper surface of the work regardless of the thickness of the work, connections are provided for moving the thread finger carrier toward and from the work with the presser foot. These connections include a forwardly extending arm on the carrier 50 (see Fig. 6) in which is secured the left end of a bar 82 having an enlarged right end of rectangular section slidingly mounted in a slot 84 formed in an upwardly projecting portion of the presser foot lever 32, the axis of the stud 52 with which the carrier 50 rotates being in line with the axis of the fulcrum pin 34 for the presser foot lever, as shown by the dot-dash line 85 of Figs. 6 and 10. By reason of the connection formed by the bar 82 and the slot 84 in the presser foot lever, the position of the thread carrying finger always corresponds in a vertical position with that of the presser foot, but the presser foot is left free to move horizontally in the direction of feed without imparting a corresponding feeding movement to the thread carrying finger 26.

The loop detaining finger 28 is formed with an S- bend (Fig. 6) to avoid interference with the other devices operating at the sewing point, the lower end of the detaining finger being pointed and directed at a slight inclination downwardly toward the left. To prevent displacement of each locking loop after being inserted within a needle loop, the loop detaining finger enters the locking loop along the horizontal portion of the thread carrying finger, the thread carrying finger having along its lower rearward side a cut-away portion 86 within which the detaining finger enters the locking loop (see Fig. 11). The loop detaining finger has a rounded point 88 which moves into actual engagement with the surface of the work and forms a definite indentation therein. In a desirable form of the detaining finger it is also provided with a locking thread loop tensioning enlargement 90 (see Fig. 12) for insuring that sufficient locking thread will be withdrawn from a locking thread supplied before each needle loop is drawn into the work to prevent retraction of the locking loop from the needle loop by reason of elastic contraction in the locking thread as the detaining finger is being disengaged from the locking loop. To render the tensioning enlargement effective, mechanism is provided for actuating it into engagement with the work and the position of the locking thread carrying finger relative thereto causes the detaining finger to be carried to a position of engagement with the locking thread beyond its tensioning enlargement before the detaining finger is disengaged from the work,

The mounting and actuating mechanism for the loop detaining finger 28 are shown in Figs. 6 and and include a split clamp at the left enlarged end of a rod 92 adjustably secured within a second split clamp at the forward enlarged end of a bar 94. The bar 94 is similarly secured in a split clamp on an arm 96 fixed to a shaft 89 (Fig. 6) running through hearings in spaced portions of the presser foot lever 32 between which spaced portions the arm 96 is disposed. Also secured to the shaft 98 is an actuating arm 100, at the free end of which is mounted a ball-headed stud 102 surrounded by a socket at the forward end of a link 104. The rearward end of the link 104 has a socket for a ball-headed stud 106 mounted in an arm of a bell crank 108 rotatable on the shaft 70. A rearwardly extending arm of the bell crank 108 carries a roll 110 (see Fig. 4) engaging a groove in a face cam 112 keyed to the sewing shaft 78. The shaft 98 is held in its hearings in the presser foot lever 32 at a position forming a small angle between its axis and that of the presser foot fulcrum pin 34, the inclination being such that the axis of the shaft 98 approaches the axis 85 of the presser foot fulcrum pin at the right end of the presser foot pin so that the head of the stud 102 is always close to or intersecting the axis 85 of the presser foot fulcrum pin. The ball stud 66 in the connections for actuating the thread carrying finger also is disposed close to or in the axis 85 of the presser foot fulcrum pin. With this arrangement there is little or no change in the positions of the thread carrying finger and the loop detaining finger relatively to the presser foot as the presser foot moves toward and from clamping engagement with the work and the detaining finger is capable of independent movement into and from engagement with the work while the presser foot clamps it.

To insure that each loop of locking thread 60 will be introduced in a needle loop accurately at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work, and that the loop detaining finger 28 will engage the upper surface of the work with certainty to prevent escape of a locking loop while the thread carrying finger retracts from the needle loop, the connections for actuating the thread carrying finger and the detaining finger are proportioned to bring the pivotal joints formed by the studs 66 and 102 in their respective actuating connections exactly into line with the axis 85 of the presser foot fulcrum pin 34 when the respective fingers reach the limits of their actuated movements. Thus, when the thread carrying finger has reached the limit of its loop introducing movement within a spread needle loop (Fig. 17), the stud 66 is exactly in line with the axis 85 of the presser foot fulcrum pin 34. Similarly, when the lower point 88 of the loop detaining finger reaches a position where it extends a short distance below the work engaging surface of the presser foot at the limit of its work engaging movement, the head of the stud 102 is exactly in the axis 85. The mechanism for actuating the loop detaining finger 28 is so adjusted that the finger always forms an identation in the work, as indicated at 114 in Figs. 22 and 23.

The loop lifter and spreader 6 has a vertical shank, the upper end of which is clamped within a transverse opening in a horizontal shaft 116 (see Figs. 1 to 4) mounted for rotation in spaced bearings at the right end of a bracket 118 secured by screws 120 (Fig. 1) to the head frame 38 above the sewing point in the machine. The lower end of the loop spreader is forked with one portion provided with a hook 122 (see Figs. 8 and 9), to act in the usual way in entering and spreading one side of each loop carried by the hook of the needle from the other side. The hook portion 122 of the spreader is located in the position shown in Fig. 16 at the rear of the path of the needle while the threaded needle is retracting from the work. As soon as the point of the needle has reached the level of the hook portion 122 the loop spreader moves forwardly to the position of Fig. 17, spreading the loop into a triangular shape. After the thread carrying finger 26 introduces its loop of locking thread, the loop spreader moves rearwardly until its hook portion 122 crosses to the rear of the needle path. In this position of the loop spreader it performs its second function to cast off the loop of needle thread from the needle hook.

To cast off the thread from the needle hook the second portion of the fork at the lower thread engaging end of the loop spreader has a thumb-like thread retractor or projection 124 which, during the final rearward movement of the loop spreader, moves into close proximity or in actual contact with the needle below its hook (see Figs. 20 and 21). After reaching the limit of its rearward movement, the thumb projection 124 moves beneath the horizontal side of the needle loop and the needle is moved downwardly a short distance (dotted position- Fig. 20), causing the thumb projection 124 to wipe the thread out of the needle hook and to shield the needle from re-entry of the thread. In this way, stranding of the thread by incomplete release from the needle hook, or the use of additional thread handling devices to retract the needle loop from the needle hook, is avoided. Thus, the thread retractor is combined with the loop spreader.

A common difiiculty has been encountered in the operation of prior loop lock stitch shoe sewing machines from irregular tensioning of the threads in the stitches, and particularly from failure to provide sufficient slack in the locking thread to enable each loop surrounded by a loop of needle thread to be pulled uniformly into the work to a depth where the locking loops always are concealed. The results of such irregularities are a spasmodic exposure of locking loops along a seam with consequent objectionable appearance or a tendency for the locking thread to cut the upper surface of the work between perforations to an extent which weakens the work.

To overcome the difiiculties noted above, the illustrated machine is provided with a locking thread controller acting to withdraw locking thread from the locking thread supply during each sewing cycle and to give up the withdrawn locking thread in slack condition after each locking loop has been introduced into a needle loop and while the take-up is drawing each stitch into the work to set that stitch. The locking thread controller comprises an upwardly extending arm 126 (Fig. 6) secured to the left end of the combined loop spreader and thread retractor shaft 116 and the controller is provided with a flanged roll 128 rotatably mounted on a bolt 130 carried by the upper extremity of the arm 126. The length of the arm 126 is such that the roll 128 swings in a path passing between the terminals of a U-shaped thread guide 132, a rearward shank of which is made fast by screws 134 (Figs. 2 and 3) to the upper surface of the bracket 118. The terminal of the U- shaped plate have vertically alined guide eyes through which the locking thread 60 passes from its source of supply. When the shaft 116 is oscillated, the roll 128 withdraws and gives up locking thread in proper timed relation to the movements of the other stitch forming devices, so that the spreader and locking thread controller are actuated together to give up looking thread after each spread loop is released from the needle by the spreader.

The course of the locking thread 60 is best shown in Fig. 3, wherein it is shown running upwardly from the guide plate 132 about a pulley 136 and horizontally to a second pulley 138, both of which are rotatably mounted on a bracket 140 secured to the frame of a wax pot 142. From the pulley 138 the locking thread runs downwardly into the wax pot about a pulley 144 within the wax pot and upwardly through a thread stripper to a yielding arm 146 of a thread supply device similar to that disclosed in U. S. Letters Patent No. 1,909,157, granted May 16, 1933, in the name of E. E. Winkley. As the thread controller operates, it overcomes the friction of the locking thread produced during its passage about the guide rolls and the thread stripper in the wax pot 142, and gives up thread free of tension at the proper time to the other stitch forming devices.

The looper 8 and its actuating mechanisms are similar to those utilized in Patent No. 1,169,909 in which the looper is supported so that it can be moved forwardly and rearwardly, on the one hand, and laterally, on the other, by two separate mechanisms. The looper is supported in a socket on a U-shaped link 148 (see Fig. 7), a forward end of which is pivotally connected to a link 150, in turn similarly connected to the forward end of a cam actuated lever 152. The rearward end of the 10 link 148 is pivotally connected to a bell crank 154 comprising the second actuating mechanism. The lever 152 and the bell crank 154 carry rolls, in turn driven by cam grooves in a drum 156 secured to the sewing shaft 80.

The operation of the illustrated machine will be better understood by reference to Fig. 24. In this figure the Needle and Awl curves have superimposed upon them sectioned areas corresponding to a maximum thickness of work intended to be operated upon by the machine. As illustrated, work of a A" maximum thickness is intended to be sewn and the motion imparted to the awl causes it to penetrate this thickness of work. The Looper and Thread Hook curves show conventional movements of these stitch forming devices and the Looper Spreader curve is modified from that in prior machines to bring its needle thread retractor projection rearwardly toward the needle at a position of approximately 208. This rearward movement is sooner than is customary, the needle dipping at this time to assist in disengagement of each loop of thread therefrom.

The Locking Thread Finger, as shown by its curve, enters each needle loop at approximately 260 and immediately is retracted, the locking thread-detaining finger entering the locking loop introduced by the locking thread carrying finger immediately after being introduced. The simplicity of the take-up motion is indicated by the curve designated as Take-up, in which a gradual movement to give up thread to the other stitch forming devices occurs from a zero starting position of the sewing shafts and is terminated at 250. A reverse movement of the take-up then pulls down each needle loop with a relatively gradual movement until the stitch is set. The locking thread controller gives up looking thread simultaneously with the pulling-down movement of the takeup, the needle thread locks of the measuring mechanism being actuated to release the thread measured while the take-up is pulling each needle loop down into the work to set each stitch, especially between the times in which each locking loop is released by the loop detaining finger 28 and in which the stitch is set.

The work is fed by a clamp comprising the work support and presser foot at the time shown by the Work Feed curve. Feed occurs throughout the time each stitch is being set from approximately 185 to 335. During this time the locking thread-detaining finger engages the upper surface of the work and moves with the work to assist the feed. The Presser Foot Lift and Presser Foot Lock Release curves, aside from being adjusted for use with those of the other stitch-forming and work-feeding devices, illustrate conventional movements in the presser foot, which is disengaged from the work during the back feed of the work support and presser foot. The presser foot is then brought yieldingly into engagement with the work where it is locked during the remainder of one sewing cycle from 120 to 360 and continuing from O to during the succeeding sewing cycle.

The nature and scope of the invention having been indicated and a particular embodiment having been described. what is claimed is:

1. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, means including a loop spreader for opening each loop of needle thread into a fixed triangular shape, a work support toward which the needle operates and against which the work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and needle thread measuring mechanism separate from the needle for varying the amount of thread provided for each stitch in accordance with the thickness of the work, in combination with means for inserting a loop of locking thread into each needle loop including a locking thread carrying finger connected for movement with the presser foot as the work varies in thickness to enter each spread loop of needle thread between the work and the upper leg of the spread loop a uniform distance from the presser foot engaging surface of the work with all thicknesses of work.

2. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, means including a loop spreader for opening each loop of needle thread into a fixed triangular shape, a Work support toward which the needle operates and against which the work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and thread measuring mechanism separate from the needle for varying the amount of thread provided for each stitch in accordance with the thickness of the work, in combination with means for inserting a loop of locking thread into each needle loop including a thread carrying finger acting to enter each spread loop of needle thread between the work and the upper leg of the spread loop, and a carrier for the thread carrying finger connected for movement with the presser foot as the work varies in thickness to maintain the thread carrying finger at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work.

3. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, means including a loop spreader for opening each loop of needle thread into a fixed triangular shape, a work support toward which the needle operates and against which the work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and thread measuring mechanism separate from the needle for varying the amount of thread provided for each stitch in accordance with the thickness of the work, in combination with means for inserting a loop of locking thread into each needle loop including a thread carrying finger acting to enter each spread loop of needle thread between the work and the upper leg of the spread loop, and a carrier for the thread carrying finger, and connections between the thread finger carrier and the presser foot for actuating the thread finger carrier with the presser foot as the work varies in thickness to cause the locking thread carrying finger to move in a path a uniform distance from the presser foot engaging surface of the work with all thicknesses of work.

4. A loop lock stitch shoe sewing machine having stitch forming devices including a hook needle, a loop spreader at the side of the work with the needle for opening each loop of needle thread into a fixed triangular shape, a thread carrying finger and work clamping and feeding devices including a work support toward which the needle operates and against which the work is pressed by the thrust of the needle and a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and to feed the work while clamped, in combination with a carrier on which the thread carrying finger is mounted for movement into and out of each loop of thread carried through the work by the needle and a sliding connection between the thread finger carrier and the presser foot movable with the presser foot as the clamping position of the presser foot changes with variations in thickness of the work but slidable in the direction of work feed without imparting movement to the thread carrying finger during feeding movement of the presser foot.

5. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, means including a loop spreader for opening each loop of needle thread into a fixed triangular shape, a work support toward which the needle operates and against which the Work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and thread measuring mechanism separate from the needle for varying the amount of thread provided for each stitch, in combination with means for inserting a loop of locking thread into each needle loop including a thread carrying finger and a locking loop detaining finger both mounted for movement with the presser foot as the work varies in thickness to cause the thread carrying finger to enter each loop of thread retracted from the Work by the needle at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work, the loop detaining finger acting to pass through the locking loop into engagement with the surface of the work with all thicknesses of work.

6. A loop lock stitch shoe sewing machine having a curved hook needle operating to carry a loop of thread through the work, a work support toward which the work is pressed by the thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and a presser foot mounting lever having a fulcrum about which the presser foot swings toward and from the work, in combination with locking loop forming and introducing devices mounted for movement about an axis in line with that of the presser foot lever fulcrum to cause each loop of locking thread inserted in a needle loop to enter that needle loop at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work.

7. A loop lock stitch shoe sewing machine having a curved hook needle operating to carry a loop of thread through the Work, a Work support toward which the work is pressed by the thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and a presser foot mounting lever having a fulcrum about which the presser foot swings toward and from the work, in combination with locking loop forming and introducing devices mounted for movement about an axis in line with that of the presser foot lever fulcrum to cause each loop of locking thread inserted in a needle loop to enter that needle loop at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work, said locking loop inserting devices including a locking thread carrying finger and a locking loop detaining finger acting to enter each loop of locking thread and to engage the surface of the work while the thread carrying finger retracts from a needle loop.

8. A loop lock stitch shoe sewing machine having a curved hook needle operating to carry a loop of thread through the work, a work support toward which the work is pressed by the thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support and a presser foot mounting lever having a fulcrum about which the presser foot swings toward and from the work, in combination with locking loop forming and introducing devices including a locking thread carrying finger mounted for movement about an axis in line with that of the presser foot lever fulcrum to cause each loop of locking thread inserted in a needle loop to enter that needle loop at a uniform distance from the presser foot engaging surface of the work with all thicknesses of work, and connections for actuating the thread carrying finger including a pivotal joint in line with the axis of the presser foot fulcrum.

9. A loop lock stitch shoe sewing machine having a hook needle operating to enter the work and to retract to a fixed position with a loop of thread, a loop spreader for opening each loop of needle thread into a fixed triangular shape, a work support toward and from which the needle operates and against which the work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support, a carriage to which the work support is secured, a lever to which the presser foot is secured tulcrumed on the feed carriage and a locking thread carrying finger for inserting a loop of locking thread into each loop of needle thread, in combination with a locking loop detaining finger mounted on the presser foot lever for movement toward and from the work with the presser foot and for independent movement into and from engagement with the work while the presser foot clamps it.

10. A loop lock stitch shoe sewing machine having a hook needle operating to enter the work and to retract to a fixed position with a loop of thread, a loop spreader for opening each loop of needle thread into a fixed triangular shape, a work support toward and from which the needle operates and against which the work is pressed by the work entering thrust of the needle, a presser foot acting at the side of the work from which the thrust of the needle is exerted to clamp the work against the work support, a carriage to which the work support is secured, a lever to which the presser foot is secured fulcrumed on the feed carriage and a locking thread carrying finger for inserting a loop of locking thread into each loop of needle thread, in combination with a locking loop detaining finger mounted on the presser foot lever for movement toward and from the work with the presser foot and for independent movement into and from engagement with the work while the presser foo-t clamps it, and mechanism for actuating the loop detaining finger toward and from engagement with the work while the presser foot clamps it, comprising a pivoted joint in line with the axis of the presser foot fulcrum.

11. A loop lock stitch sewing machine having a hook needle operating to enter the work and to retract to a fixed position with a loop of thread, a looper for laying the thread in the hook of the needle, and a device for introducing a locking thread into each loop of needle thread, in combination with a loop spreader for opening each loop of thread carried through the work by the needle into a fixed triangular position and formed with a projection for wiping the thread out of the needle hook after the locking thread has been introduced within the needle loop.

12. A loop lock stitch sewing machine having a hook needle operating to enter the work, to retract to a fixed position with a loop of thread and to dip in releasing its thread loop, a looper for laying the thread in the hook of the needle, and a device for introducing a locking thread into each loop of needle thread, in combination with a loop spreader for opening each loop of thread carried through the work by the needle into a fixed triangular position with one angle held by the needle and formed with a needle loop releasing projection and mechanism for actuating the loop spreader while the needle dips to disengage the thread from its hook.

13. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, and a loop spreader for opening each loop of needle thread into a fixed triangular shape, and a device for introducing a loop of locking thread within the spread loop of needle thread, in combination with means including a locking thread controller acting to give up slack locking thread after the locking loop has been introduced within each needle loop.

14. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, and a loop spreader for opening each loop of needle thread 14 into a fixed triangular shape, and a device for introducing a loop of locking thread within the spread loop of needle thread, in combination with a locking thread controller, and mechanisms connected to the loop spreader and locking thread controller for actuating both together to give up slack locking thread and to release each needle loop spread by the loop spreader.

15. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract to a fixed position with a loop of thread, a loop spreader for opening each loop of needle thread into a fixed triangular shape, a device for introducing locking thread within each spread loop of needle thread, in combination with means including a shaft to which the loop spreader is secured and a locking thread controller also secured to the shaft for giving up slack locking thread after being introduced into each needle loop.

16. A loop lock stitch sewing machine having a hook needle operating to enter the work and to retract with a loop of thread and a locking thread carrying finger for introducing a loop of locking thread into each loop of needle thread retracted from the work by the needle and thereafter to withdraw from the locking loop, in combination with a locking loop detaining finger acting to enter each loop of locking thread and to prevent its withdrawal from a loop of needle thread during withdrawal of the thread carrying finger, the loop detaining finger being formed with a locking thread tensioning enlargement to cause locking thread to be withdrawn from its supply as the detaining finger is being disengaged from the loop of locking thread.

17. A loop lock stitch sewing machine having a hook needle operating to enter the work and to retract with a loop of thread and a locking thread carrying finger for introducing a loop of locking thread into each loop of needle thread retracted from the work by the needle and thereafter to withdraw from the locking loop, in combination with a locking loop detaining finger acting to enter each loop of locking thread and to prevent its withdrawal from a loop of needle thread during withdrawal of the thread carrying finger, the loop detaining finger being formed with a locking thread tensioning enlargement, and mechanism for actuating the loop detaining finger into engagement with the work with its tensioning enlargement carried beyond the position of engagement of the locking thread with the detaining finger to cause the enlargement to withdraw the locking thread from its supply as the detaining finger is being disengaged from the work.

18. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract with a loop of thread, a locking thread carrying finger for introducing a loop of locking thread into each loop of needle thread retracted from the work by the needle and other stitch forming devices, in combination with means including a locking thread controller acting to withdraw locking thread from its supply during each sewing cycle and to give up slack locking thread after each locking loop has been introduced into a needle loop.

19. A loop lock stitch shoe sewing machine having a curved hook needle operating to enter the work and to retract with a loop of thread, a locking thread carrying finger for introducing a loop of locking thread into each loop of needle thread retracted from the work by the needle, and a take-up acting on the needle thread to give up thread to the needle as the needle retracts from the work, in combination with means including a locking thread controller acting to withdraw locking thread from its supply during each sewing cycle and to give up with drawn locking thread in slack condition while the takeup is drawing each stitch into the work.

20. A loop lock stitch sewing machine having a curved hook needle operating to enter the work and to retract with a loop of thread, a locking thread carrying finger for introducing a loop of locking thread into each loop of needle thread retracted from the work by the needle, needle thread measuring devices for providing needle thread in an amount varying with the thickness of the work, and a take-up for setting each stitch, in combination with means including a locking thread controller for withdrawing locking thread from its supply during each sewing cycle and for giving up the withdrawn locking thread in slack condition after each locking loop has been introduced into a needle loop and while the take-up is drawing each stitch into the Work.

21. A lock stitch sewing machine having a curved hook needle operating to enter the work and to retract with a loop of thread, devices for interlocking each loop of needle thread with the locking thread and for setting each stitch, in combination with integral means including a combined loop spreader and retractor for opening each loop of needle thread into a triangular shape during the operation of the thread interlocking devices and for casting oil the thread carried by the needle hook.

22. A lock stitch sewing machine having a hook needle operating to enter the work and to retract with a loop of thread, devices for interlocking each loop of needle thread with the locking thread and for setting each stitch, in combination with a combined loop spreader and retractor for opening each loop of needle thread into a triangular shape during the operation of the thread interlocking devices and for casting off the thread carried by the needle hook, said combined loop spreader and retractor being formed with a fork at its thread engaging end, one portion of which is provided with a loop spreading hook and another portion of which has a retractor projection.

23. A lock stitch sewing machine having a hook needle operating to enter the work and to retract with a loop of thread, devices for interlocking each loop of needle thread with the locking thread and for setting each stitch, in combination with a combined loop spreader and retractor formed with a fork at its thread engaging end, one portion of which is provided with a loop spreading hook and another portion of which has a retractor projection, and mechanism for actuating the combined loop spreader and retractor in one direction to engage the hook portion with the needle loop and in the other direction to cause the projection thereof to wipe the thread from the needle hook.

References Cited in the file of this patent UNITED STATES PATENTS 431,192 Peirce July 1, 1890 612,150 Bean Oct. 11, 1898 1,106,800 Goddu Aug. 11, 1914 2,541,608 Pravda Feb. 13, 1951 

